Camshaft adjusting devices are used for particularly accurate and fine control of the combustion in an internal combustion engine.
For this reason, one or multiple inlet valves is/are adjusted relative to a driving element, such as a crank wheel, which is driven via the crankshaft with the aid of a traction means drive. However, the outlet cams may also be adjusted.
The use of two camshafts is known from the prior art, for example DE 4226798 A1, the outer camshaft completely encompassing the inner camshaft, at least in sections. The inner camshaft is supported within the outer camshaft.
DE 4226798 A1 discloses a reciprocating internal combustion engine which has two gas exchange valves per cylinder. Two inlet valves of an internal combustion engine cylinder system are actuated by two cams which are adjustable in relation to each other with regard to their phase angle. In addition, the phase position of both cams is variable in relation to the internal combustion engine crankshaft. The charge exchange dynamics of the internal combustion engine may be determined by the so-called variable cam phasing and the variable spread.
DE 4226798 A1 discloses a structural specific embodiment having a single, longitudinally movable positioning bolt which has at least two inclined toothed areas, with the aid of whose shifting movement both the phase position of both cams and their mutual phase angles are changed.
In conventional designs, a sealing cover of this adjusting device is fixedly connected, in particular rotatably fixedly connected, to the outer camshaft or an integral part of the outer camshaft, in an adjusting device, in particular a hydraulically active adjusting device. Pressing elements are usually used for this purpose
Due to the fact that the adjusting device frequently has a central screw which is screwed into the inner camshaft and axially fixes a rotor, which acts as the adjuster, relative to the inner camshaft with the aid of an outer shoulder of the central screw, the overall configuration having the inner and outer camshafts is axially fixed with the aid of the adjusting device.
In some specific embodiments of camshaft adjusting devices, however, it is not desirable to have a fixed connection between the sealing cover of the adjusting device and the outer camshaft. However, it is nevertheless still desirable to fix the inner camshaft in a rotatable yet axially determined manner.
It should be noted that a wide range of specific embodiments of phase adjusters exists.
Driving a concentrically situated camshaft with the aid of a vane is less common, since the design is particularly complex.
As mentioned above, the rotor is frequently rotatably fixedly connected to the inner camshaft via a central screw. With the aid of the axial bearing clearance, this rotor determines the axial position of a stator, which is axially shiftably supported on the outer shaft.